Ikki was injured; he was walking oddly for a good month, the nurse and doctor that were tending to Sora noticed it when Ikki came into that hospital room. The injury just wasn't as serious as Mikagami claimed it to be--instead of busting up his knee, he simply... Bruised it, I think?

It was completely healed long before he was released, he stayed for as long as he did because of Sora's training.

Even Japanese have to sometimes look up kanji in a dictionary because they're numerous. As for translators, even if they aren't up to par with other team's tls, be glad they're there to provide an English transcript for the raws. At least show a little gratitude for people who devote some of their time (and believe me, private life, studies and/or work can be a bitch) to give us those cleaned up files.